SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '40c3d2a8c059948b46678c3d89878b96326b2c02d7a42023f004ae9312f391ee' 
  AND token = 'h5KnvQ1v/7SPFBOp+UUC5Bgr8tIklyxLXZ/qWT1uAJ4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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