SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '174e56e7848e04bb84577c28798402f62102a435bac959e78c9ea203ac33d46c' 
  AND token = 'nwyn9EPpIaJ6Fr5SC80UwIbD2PSHKJG8Sa2mNEWChDo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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