SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '239951937d09b15bcfda6061631f8acf9294dac3788ad39fbb95108ac8e1e611' 
  AND token = '3hLM/YeXXjliyifo4MFUpi0czf5bL2Xxzeq71B0yrC0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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