SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '300434b483bb0adcfe821619c0f7b5dcdceaf49d80d398cc46d3e76da626e780' 
  AND token = 'FWRrVKX2Vs0mkNT4s2ksRYU1KiqHOsAi3VLpu69Dl0g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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