SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '564c2b46814f4b3735c7ac8d08ad97817acf24560dcd542194055f867e19a544' 
  AND token = 'yyF3gp5pGJFfNKrSZMqbSpJgbmDjRRfvrMmFV3uTG8k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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