SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '420019dd613cf9305184637f52865f48f126eea71114ac4925f51c1c9b85481b' 
  AND token = 'pXqGIVUlEB+IdgTqlWiHF49uqqtiCWp6q/bp8JrAbvs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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