SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9de16c3eb56394fb58af2e88c14d4fbf9948cffaa65f67612ecd2f016ffbb9a5' 
  AND token = '1wItVjkf3ihG1ZE7lupu2q2dazFy5lO7BqPl+Q6MKmU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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