SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '83571266a323feecc97025998ccfc09997e7a67d528781d21b4e0a7e158cf278' 
  AND token = 'M/XSB/0H3x2ls1r13ibzv6yBAn51q+e5NDnUeuG8G8s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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