SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '611fc7976398abe389d93c4024e5040478b8198e965b2433975f34c9fb524f72' 
  AND token = 'KesGhnQY39NiWxidsqRoDmiiOxDeuC3+0FEUFKgJYSk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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