SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a6a9bfaf389bb24415f09b0622281c5bf2d06c3f725d37344e9d54f890e61d8d' 
  AND token = 'deao08doBCVpkhG3cj/94uZx2+v+7ErgHF1r/gKwyQo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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