SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '753eb392bf3a65102a7daf0f261ae811e62ba628513516ebc0dca013c9189abb' 
  AND token = 'EmGrlK6Hp5cIXAvc+sy5zwpnS2AlBnQNkRRMWGRMc2k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00010

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}