SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b749c0495d088c718f53a3631806e1d5846ea7ce3533c042687f6dfb9dfd6340' 
  AND token = 'i89qeP+8DTXZYwblxqI47CjhX6FwFJrmBNXJd49wRpM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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