SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '21e933d4627ed4e5561b512869ecfac775742c0590214c40bd2ce67c4e6c0755' 
  AND token = '/oyYzxfjPW3loH19VpYjPEYB/DbUq4qBwLu+GUlA/5Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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