SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '75dbbb5546ed6b077f91061fb76458a0f07b6240b9342813642a80c87c0c7bce' 
  AND token = 'MDjm3/EDpwjlQrNZmkSQ3wBVxrb/kqAeFtG8pyfURhU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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