SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd9248666597aca5ae16626b91bc1bf5b83bf6981a8be9fd96e88ddfc7ef03e5e' 
  AND token = 'NOB1KVKMrSYA+jjRNgF4NpahAcI/75SGHTpF0QLaWgo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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