SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '8050bc207ae4bef0fcb9b83fb0716797702a8838bd373e654a8bc0d664f1d5fc' 
  AND token = 'rZRpBVbszLgMcD1Jq8LKl9m7dEfmmshCQFBiOLfcw5o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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