SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ec77d831567377ada08c175881048279862198c767cb3b7341f85ad0918af570' 
  AND token = 'Wc6wURkLVEV4mfchxdF77B/sfSjTdh3VN8t/QmNkhj4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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