SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fb96dee528cfa1b5cfd1ed92982af5fdd3b301e0803a703046d04b113ca03794' 
  AND token = 'zUJ2Rn5TM0h/xNgwklzJy4ElROpAWLgdsjy3L7fwCd0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00047

JSON explain

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