SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f17c87ff000bad4c8888ff6a758e2d0a6388ad11ddcde5e4503cd71cbe9a0da8' 
  AND token = 'Y+/ZyowKjU2hlILhUSBjP2xYMN/Zk5mPQHTrlLwdubU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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