SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f235bff78b8b77301e07acdb8731f3b290025841e98b86c2caa384ccca6f9796' 
  AND token = 'lxjNjboXTbwVKYJKaZg2AXERCLc9Rfye7Q+ZHSS/TMw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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