SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '334330990b03ecc88217baf4817c2a9f4d8e4a36b396ac63d35ba720dd94b620' 
  AND token = '5qOkBlbZNpvvrniB0UQ8/Bbm39eEwBpXdMIEOPM8Dsk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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