SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '19e7f8f84b56fcb43114dda71c2309b8a5b434b28c44e47c0d82fc904da0764a' 
  AND token = '/uZTRO9OI3q1xeUgHQiKpbqk8zxxp8u9gv4yXSdOjzM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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