SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '53aa62990ffc938a394056316b321192273dcc607d8f64709284b124125cafda' 
  AND token = 'iWUR3x/q8/CR0gQjhC7kaPUM3OCiq0jQeS65CvOZPmI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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