SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '1ace39b02c63ef3d74d90d7809cf7faebee346fe418cce0ed337171961f81ee2' 
  AND token = 'ZixjFIn4206ZdiudxSvxqxp3MEKRWD5laeLJ4EYdOCs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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