SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '207c8a7693b71f2ee9f1dd3f39187eec3ebcad86a51d05884783e97569e5bef2' 
  AND token = 'mLh4UtWwVJ7MGKfmni9K75FNNhrsH8Y/0OR/uEjRJWo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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