SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8c9cadfec5ded0f6c8c1ab2c9a9e740afa656179fb7707fc3b9397e2dfee6b8b' 
  AND token = '5NB42wjnBzkTmuw+uBe2Qvmi0KoFFJagkPXJ/+HWoyQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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