SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1c45e1639c039beaa8551b9acfbb2e486a11a24a83ef486b43fb62ce6edcd5fb' 
  AND token = 'x8kp/kxhwQNqwwVkrsCZ0tEF6kxpPXlHjo2RjsWQpUQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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