SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fa666f20b6abb519c46d462ead476d5525ffdbda110ed02278980eadad8745d2' 
  AND token = 'xdugGwKndGzjm1J/yJ4u+FXhxSVcJIKcsl1z5A6vfwQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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