SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2d873c05979a04caf37973a7b7d9c4dc2f1b7aac5cd339ad3920cf9a8c8d14c9' 
  AND token = 'mg3gsk/rKkdG7CF+Lbr4xfwp+h+Uk6QAQpxK1fESD3E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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