SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b3fe743d0429c17999e8f64f093f7852ab9283488bcf94e51482606a3669199f' 
  AND token = 'PiALr402nbRgZ/sQGMO381Qp0YrphsurFFVEJibOSJE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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