SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1c91946177ebcf70c036143d661235eb5ceb4c8976f9dc16721f82773e399c4f' 
  AND token = '7s/JRCWJTTmm3k2VccYmJcJ1d8bOKF6CvxcfvwVhe3M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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