SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8c79ccb1cfa89d309b1d4375c72b0053f9ab7918ec2ce19ca8bf1b39ae00fd3a' 
  AND token = 'Z8nUfgJ5xQUuTGettCQPFYfx6YCnsoZWZoyUJkTRi0U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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