SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c6e5ce41d5073b27b3e2f447c0bf91e5bba16a0ecc13f76c1fd46d3660d72c5f' 
  AND token = 'l+n0z21HIEphPNEgcVWhXTvG5KLYCU3GwIjlm9RzSN8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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