SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '46ca23982bdeecfb6a196c089a182fd486ab055c0fbcb07a1767756773164a55' 
  AND token = 'ndzUiP4iGSdbGBBEVdht8v0HHW9ejvSueHw6/5NrNX4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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