SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cd4382975ff521ee80b037eb66ffa944c661a6610eaa6c20613358b8858aecd2' 
  AND token = 'CrCSravb3k/oaeUtAKGFJTVGgMGmxSy7zwaPJ5qaMSc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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