SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fe6c18aa7d744d61873dd397f9118b536b501f524a996ee2fffabaf847314f1d' 
  AND token = 'asoyM8KT3M5r54ppBk1l+HYDfDWVdproaGcWP05cMME=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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