SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2fbcd933ce2052da79415bbae08619b920d58d1e296442b2ad2966be90935475' 
  AND token = '7Ur+iyCTzZbXWayPlvG7Bma96rdJDLEIosBmRSjpLnY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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