SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9b5e460ede316a2baf4100d52bed6bc98fd790bed375c0888e972d51eb253f57' 
  AND token = 'GZYi4n8Nji7kNhzJLxjFh8bVY6GRRBToGxeovwcpoI0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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