SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6db57935f4e48deb2111561087198d0b9447cca85ab1c037303eebabd1452939' 
  AND token = 'S7vBZHD/pWKXNf1RgJrtLjnq4OMHjlIoOQg4DhFBBwM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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