SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2386616c1b9d0d6cf0249d60a178e6adffdbedfc516e425a205c98ad5bf74c1a' 
  AND token = 'lMJiL2GZnyZC1lhrdmS+UY7A3ikn/MfQ4EYPKRrmRhU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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