SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'b70c7d5fb5991dcc415040be4b2150a1fe9d1556574876702a1273ee5852d5bd' 
  AND token = 'QrGQsuECIUaddDKF30WdejUNNm1yq5DZgaFJAotbS+g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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