SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3581775dd1f67afdf40988162723309c6569d39667b03c2cbb8ffdebea8cad38' 
  AND token = 'RCNR5DTIVJ9QwOLfI9alHe6bt1BxbpxVvBk2xjuCKH4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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