SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5bbf64c47983be9de0a0846e103a95b3809e6e571dbea13851678d8765d8848e' 
  AND token = '9jqTcSWBS4KOnBhkguIGYH8rzWPTneJOsNhcb21zT6Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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