SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5429b3cfbe17498632ae04d962a6760b23bb372717e62bd0c32ac2ac21b3912c' 
  AND token = 'rV7UwDEelomeuvu81CtkikhNOU9YmUlBHCFGXfzPHnM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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