SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '66da07e8038ad7f663ba15d47968dd6d14224c1d14728d8aba61c5c8022d8184' 
  AND token = '8k6jFKmuthOjLcYveV7vo66983eaGpv/4+RxvfNmVbA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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