SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b23cadf4dc02214de352dd883739fa9249f8aed37f26350d0f4282cbfc416591' 
  AND token = 'mXD5srOqdS4Yo2mWQVG2QQuaNWs9pv57HRvbbkWMfAQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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