SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '75343ec9aff1597ce7817f66251d420de1cb6ec02be35e46aabb753b6d9475c4' 
  AND token = 'gcARJ4o2WFOWVMeY70xdaBfK4Hw5JSroELr9DJJ6qPQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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