SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a63abb15c729198bf6ed7bb236d4346c00b1937c7b12962d276a40878595ff7f' 
  AND token = 'TzGaUzI1wvqPStlk+knmp2ZV0IoVlQ1miIv1AjOV0eg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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