SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '60eff3c78f4e88362f39246a111135698bfe2cb085021aff2d042d6fa39f1f20' 
  AND token = 'OPsB9ZbfiVPfL57UXDOeiBOb3VWOsKamTIN1GdGoxFM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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