SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f837a1834464d6911d75e15e33ad944fb1713be0e1d387fc24357db7fb6d2ce6' 
  AND token = '5QppB1R3nFYW2vE671A3cv+qj3rdftgtsEhNlXJrieY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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