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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c15bed5151d8c0d4ba67d3ed6e0823e0f7a7178dfb67b3d2b588bd101ed7a974' 
  AND token = 'dRYkZNKQC26C5lPpT1mkfWcazogWJcBzQhLhL+JAyrw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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