SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0555ee1655fad97f92242271fb6259ef7f55f47606e5030d613aef979f60101f' 
  AND token = '0W+pERbDK7nkwkWAnPAAPt0zFgwRjeFnAuCMtFyAH0Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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