SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9f848b4348047c9713bb49902933639566693d910c3af5f74c785bbc68dd2187' 
  AND token = 'gnCGiTcNOPqY4so+8Ycpauy/2XfzwWR0xY4e/uvWTjs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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