SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '76ad8598869dc939dbfd6d45e5e214f465c75eafd38d78093125b6ec15d1b0e9' 
  AND token = '6oVEbsqBDkJWxOqYo6Wn5VF4tpYVjnNjMBy8z+wqS/8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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