SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ef58e9c7e619c1abe5e3c73a9b81d1824b03ff9abdebb1a7a57450c83b30b463' 
  AND token = 'doHK+y1Aytgzf8KcXJtSJzj0vR8Pol4DCOoQFJ5pHD4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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