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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cad47e6e867d8897afef2837e8a350281cf8019282d60f6c1c0b43fce3a07fbe' 
  AND token = 'a6f8REx4FuRW2OneAgdOnsVI0p+mezGqDQAtLAC82Uw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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