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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a92dd0ce782b104b2e170f4540164e71fe3616c7f2eb3f42bb634e65857c1f54' 
  AND token = 'PRw3dPRH67CUcgcqv8FtLM3NUs6axfoDRuzp+t/Ur7I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}