SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7bbf19a2139c7dbc4b33702b830840e9e868814aa64012480ef2925ebc8b70cf' 
  AND token = 'c/k+qKP2+NhGmvzds72Qj5kpd+sx4w5HpAX5JsGBV80=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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