SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8ad2cca13cc2395c17481cbee58b55beda0e41b65e560af1361404c1db1fd4c1' 
  AND token = 'bfePprzB2vYXtBuKGATpVv/5nNpAxOBB9vcaaVn9+qw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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