SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9b3e8b4c5c9f8def9bdd72684864951dddaeba628104c4603c0e2a44cc6faab5' 
  AND token = 'IETkvRWPNDodst05VVexQBaTNQ0zB/EruacD95MMWNo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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