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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c1cfdd99634f9b9ab0b513d62359d77941165d51ff5c5579f9acce5f7374b856' 
  AND token = 'oiulBkDZzTOyG9oV94FqQRkfr88fEW2+aRxL2fucCn4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}