SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c1735efcaa191b290ba00f10b99448487625cf4b46644152d11af585238666ad' 
  AND token = 'ThQ43vLznujlDBQjdtTiw2DRsNNVGqBWrtEqPB2uiXg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00013

JSON explain

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